Re: [PULL] http://www.linuxtv.org/hg/~hverkuil/v4l-dvb-zoran

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On Sun, 2009-03-01 at 10:24 -0800, Trent Piepho wrote:
> On Sun, 1 Mar 2009, Hans Verkuil wrote:
> > > Even though kmalloc supports higher order allocations now, they can
> > > easily fail.
> >
> > The right approach which most drivers take is to allocate up front when the
> > driver is loaded. Zoran should be modified to do the same.
> 
> Still, it's a shame to waste the memory when the driver is not in use.
> There is a patch that was posted to the mjpeg list that converts the driver
> to use the pci dma api.  There is something that _is_ in the kernel called
> swiotlb that might serve as a replacement for what bigphys_area did.

I don't know what bigphys_area did, but swiotlb is enabled when you
don't have a hardware IOMMU, IIRC.  This will show up in dmesg as:

"PCI-DMA: Using software bounce buffering for IO (SWIOTLB)"

and the kernel will end up doing memcpy()'s for you.

Regards,
Andy

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